Sender overload control



M. E. MALo'N EY SENDER ovERLoAD cioNTRoL oct 27, 1953 Filed July 12. 1951 -all m. .um

/NVENTOR M. E. MALONEV Claw-za@ A TTORNEV oct. 27, 1953 M. E; MALONEY 1523657273 SENDER ovERLoAD CONTRO;l

Filed July 12, 1951 4-sheet-#h'eet 2 www N .um

A TTORNEV Oct. 27, 1953 MALQNJEY SENDER ovERLoAD CONTROL Filed July l2, 1951 /NVENTOR l M. E. MALoA/Ey 'By C- A fro/:wey

Oct. 27, 1953 M. EMALQNEY SENDER o vERLoAn CONTROL Filed July l2. 1951 /Nl/ENTOR B y M E. MALONEV C. 71am@ A TTOR/VEV 0% Y .um

Patented Oct. 27, 1953 UNITED STAT TENT OFFICE SENDER OVERLOAD CONTROL Application July 12, 1951, Serial No. 236,358

i claims. (o1. 179-18) This invention relates to automatic telephone systems employing common control equipment and has for its object to facilitate the disposal of calls which cannot be completed.

In automatic telephone systems, particularly those employing cross-bar switches, two sets of common control equipment are ordinarily employed in the completion of connections, that is registers or senders at the originating ofiice which receive the complete designation of the wanted line, and registers or senders at the oice of the Wanted line, to which the originating register transmits all or a part of the designation and which may complete the connection. If all of the registers or senders at a wanted oice are busy when the connection to that oflice is set up, the register or sender at the originating cnice cannot complete its functions at once and must wait for an idle register or sender at the wanted oice to become available. 1f the wait is too long, the timing circuit of the originating register or sender nally causes a busy or overflow signal to be transmitted. to the calling subscriber.

In the case of local telephone connections, an arrangement has been provided for rerouting calls for a particular oiilce to an overflow signal when all incoming registers at such office are busy, but this arrangement employs an individual connection to each of a plurality of originating markers, and these individual connections are set up under manual control.

In the case ci toll calls, any delay in the cornpletion of a connection is undesirable, and, in View of the distances involved, the individual connections are uneconomical.

In accordance with the present invention, means is provided for rerouting calls to overflow, or reorder when all incoming senders are busy, employing a signal transmitted over the interoiiice trunk.

More specically, when all incoming senders of an cnice are busy, a multifrequency code signal is prepared for each trunk having access to such senders. When a connection is extended to one or" these trunks, the signal is transmitted over the trunk to the originating sender, which responds to the signal to release the trunk and cause a new connection to be set up, over which a recorder or overiiow signal will be returned to the calling subscriber or operator. A

These and other features of the invention will be more apparent from a consideration of the following description when read in connection with the accompanying drawings in which:

Fig. 1 shows an incoming trunk circuit, incom- Ling trunk line and sender link Fig. 2 shows the outgoing link switches and an originating sender;

Fig. 3 shows an outgoing intertoll trunk circuit;

Fig. 4 shows an incoming intertoll trunk circuit at a distant oice and the all senders busy equipment at that office; and

Fig. 5 shows the manner in which Figs. 1 to 4 should be arranged.

Since the arrangement of the present invention nds its chief value in toll systems, it has been shown as applied to the toll system disclosed in Patent No. 2,564,441 to B. McKim and W. B. Strickler, granted August 14, 1951, and reference is made to that patent for a detailed disclosure of certain circuits shown schematically herein.

Assume that the subscriber at substation |00, which is connected with local ofce I0 wishes to talk to the subscriber at substation llliwhich is connected with local oflice 40| reached from ofiice lill through two toll oiiices. Substation lill) will be connected in the usual manner with the outgoing toll board |62, where the operator seizes a trunk |63 outgoing to the rst toll oiiice where the trunk appears in the trunk circuit of Fig. 1.

Seizure of the trunk circuit of Fig. 1 is indicated to that circuit by the connection of ground to conductor |04, thereby completing a circuit over contact 2 of relay INH) or over contact 1 of relay CO(I) to battery through the winding of relay SVH). A parallel circuit is also completed from ground on conductor |04, contact 8 of relay COU) to battery through the winding of relay LC(| Relays SVH) and LC( I) operate in these circuits.

Relay SV( l) at its contact I disconnects ground from conductor |05 and at its contact 2 extends conductor m5 to battery through resistance lamp A(I), as a signal to the calling oce that the toll oilice is not ready to receive pulses.

Relay LC(I), at its contact 2 connects ground to condenser TM( I) to insure that it is completely discharged, and at contact 4 closes a circuit from ground to battery through the lower winding of relay IN( I operating the latter relay.

Relay 1N(| locks over its contact 4 to ground independent of relay LC( I at its contact 3 connects the winding of relay LC( I) to conductor IM, independent of relay CO(||) and connects ground over its contact 'l and contact i of relay CO( I) to start conductor |96 leading to the sender link.

The sender link comprises a plurality of crossbar switches, operated under the control of a link control circuit, which selects an idle sender for use and is associated with the sender link by a control connector. These circuits are shown diagrammatically since they are essentially the same as shown in Patent No. 2,293,191 granted to A. J. Busch et al., August 18, 1942. For convenience in identifying the circuits connecting the sender with the trunk circuit the conductors leaving the trunk circuit and entering the sender will be given corresponding numerical designations in the hundred series of the respective figures, namely Fig. 1 and Fig. 2.

The connection oi the sender with the trunk and the preliminary operations of the sender, including the registration of the trunk class', take place as described in the McKim-Strickler patent.

When the sender has been connected with the trunk it grounds conductor I||J, completing a circuit through the winding of relay CO(I) to battery. Relay CO( I) operates and closes a locking circuit for itself over its contact 5 to ground at contact i of relay INH). At its contact 6|, relay CO( I) opens the start circuit for the sender link.

When the trunk class registration has been completed, low resistance ground is connected to conductor I I, operating relay SP( I) which connects the trunk conductors through to the sender.

With relay SPH) operated, the upper pair of incoming conductors are extended to the sender, conductor |68 extending through condenser TI (l), contact 2 of relay SPH), condenser TRU), conductor H5, through the sender link to conductor 2|5, contact 2 of relay LKAGZ) to the multifrequency receiving circuit 253, while conductor we extends through condenser RI (I), contact 'I of relay SPH), condenser' RRG), conductor I Eil, through the' sender link to conductor ZIJ., contact Il of relay LKAQ) to the multifrequency receiving circuit 250.

The lower incoming conductors |25 and |2| are connected together through condenser T( I), resistance T( l contact D of relay SP( I) and condenser R(|).

Relay COU) at its contact 'l disconnects relay SV(|) from conductor |34, but at this time relay SV( I) is held operated in a circuit extending from battery through its winding, in parallel through the windings of retard coil A(|), over conductors IM and H5, which extend through the sender link to conductors 2||| and 2I5, to ground through the multifrequency pulse receiving circuit as traced above. For a complete showing of a multifrequency receiving circuit, reference may be made to United States Patent 2,352,893 to McKim-Myers, granted August 14, 19 5.

Both pairs of outgoing conductors are extended to the sender, conductor |22 extending over contact d of relay SPH), conductor I Il, through the sender link to conductor 2H, contact #i of relay MT (2) to conductor 2439, and conductor |23 extending over contact 5 of relay SPH), conductor H5, through the sender link to conductor EIS, contact 5 of relay l./iT(2) to conductor ZIO. Conductors 205 and 2|@ are further extended to the particular outpulsing means as will be described hereinafter.

Conductor |24 is extended over contact I2 of relay SPH), conductor ||2, through the sender link toconductor 2|2, contact 2 of relay MT(2), conductor 205, Contact 3 of relay OP|(2), and thence over conductor 259, contact 2 of relai7 OP(2) to the windings of relay SL(2). Conductor |25 is extended over contact I4 of relay SP(| conductor I3, through the sender link to conductor 2|3, Contact'l I of relay MT(2), con- 4 ductor 20|, contact I of relay OP|(2), conductor 26S to the windings of relay SM2). These circuits are used for supervisory purposes after the trunk circuit has been connected to an outgoing trunk.

When the originating sender is ready to receive pulses, it disconnects ground from the circuit of relay SVH), permitting that relay to release. Relay SVH), in releasing, disconnects battery from conductor |55 and connects ground to that conductor as a start pulsing signal to the outgoing toll board.

The operator at the outgoing toll board |62 now transmits the calledl number by means of multifrequency pulses which are received by the multifrequency receiver 25|) which controls the setting of the called number register 25|. When suiicient digits have been registered, register 25| operates marker start relay MS2(2) over contact of relay RORI(2) and relay MS2(2) connects battery over Contact il of relay MRLC!) to the marker connector 252 to cause the connector to operate and connect the sender with an idle marker 253. The marker proceeds to select an idle outgoing intertoll trunk such as shown in Fig. 3 and operates the incoming and outgoing link switches |54 and 254 to connect the incoming trunk of Fig. 1 with the outgoing trunk of Fig. 3. It tests the continiuty of the connection and then signals the sender to release the connector 252. These operations take place as described in detail in the McKim-Strickler patent.

When the marker has selected the idle outgoing trunk it grounds conductor 255, operating relay TKS(2) which locks to off-normal ground and starts the operation or the timing circuit 255. When the marker is ready to be released, it grounds conductor 251, operating marker release relay MRL(2) which locks under the control of relay MS2(2) and disconnects battery from the marker connector 252, so that the connector 252 and marker 253 are released.

When the timing circuit 256 has completed its operation it operates relay TCA(2) which connects ground to the upper, high resistance winding of relay SM2) Referring now to the outgoing trunk circuit of Fig. 3, this trunk circuit, when idle, connects ground over contact I3 of relay OS(3), contact '5 of relay GA3), and contact 5 of relay LO(I5) to group busy conductor 305 and connects battery through the winding of relay OS(3) over contact I of relay G(3) and contact 5 of relay LO(3) to individual trunk busy conductor 30|. The marker uses these conductors in selecting the trunk for use. Having selected the trunk, the marker grounds conductor 3m, operating relay OS(3). Relay 03(3) connects ground over its contact 3 to condenser TM(3) to remove any charge that may be present. At its contact 4, relay OS(3) connects ground to battery through the lower winding of relay 6(3) operating the latter relay. Relay C+(3) locks to ground at its contact 3 and closes a locking circuit for relay OS(3) which may be traced from battery through the winding and over contact of relay 05(3), contact of relay LO(3), contact 2 of relay G(3), conductor 306, contact 5 of relay LO(3) to ground on conductor 30|.

As soon as the switches have been operated, conductors 302 to 306 of the outgoing trunk circuit are extended through the outgoing link switches and incoming link switches to conductors |22 to |25 and ||8, respectively, of the incoming trunk circuit. Conductor ||8 thence exyduct'or 403 and connects ground thereto.

tends through the sender link switches to conductor 2| 8 of the sender and over contact 3 of relay MT(2), conductor 204, contact 3 of relay MS2(2) to off-normal ground. The connection of this ground to conductor 33| provides a locking circuit for relay OS(3) under the control of the sender.

The outgoing trunk circuit of Fig. 3 is connected with the incoming trunk circuit of Fig. 4 located at the distant toll oice by means of the talking conductors 309 to SI2. Signaling between the offices takes place over conductors 302', 300, 402 and 403 through the medium of the composite signaling circuit 320.

Relay 05(3) when operated, at its contact II disconnects ground from conductor 301 leading to the composite signaling circuit 320 and extends that conductor over its contact I and contact 2 of relay SVP(3) to battery through resistance lamp A(3). The composite signaling circuit 320, in response to this signal, connects ground to conductor 402, completing a circuit over contact of relay 00(4) to battery through the winding of relay LC(4) and over contact I5 of relay CO(4) to battery through the winding of relay SV(4). Relay SV(4) at its contact 2 disconnects ground from conductor 403 leading to the composite signaling circuit 320 and, at its contact I, connects that conductor to battery through resistance lamp A(4). The composite signaling circuit, in response to this signal, connects ground to conductor 308 as a stop-dial signal.

Relay LC(4) operates relay IN(4) and initiates the connection of an idle sender through the sender link 404 with the incoming trunk of Fig. 4 at the second intertoll oiiice in the same manner as described for the incoming trunk of Fig. 1.

If an idle incoming sender is available and is connected with the trunk circuit of Fig. 4, it operates relay CG(4) and, later, relay SP(4) in the manner described for the trunk of Fig. 1. Relay CO(4) disconnects relay SV(4) from conductor 402, but that relay is held operated from the sender over conductors 406 and 401 until the sender is ready to receive pulses. Relay SPUI) extends incoming conductors 309 and 3I0 to conductors 400 and 401 to provide a path for the multifrequency pulses to the sender and connects incoming conductors 3|| and 3|2 together through resistance TUI). When the sender is ready to receive pulses, it releases relay SV(4) and that relay disconnects battery from con- The composite signaling circuit responds, removing ground from conductor 303 and connecting battery thereto.

With ground connected over lthe contact of relay TCA(2) to the high resistance upper winding of relay SM2) parallel circuits are closed as previously traced to conductors |24 and I 25 which are now extended through the trunk link switches to conductors 302 and 303, through the windings of retard coil AI (3), and through the upper and middle windings of relay LO'(3) and thence in common over contact I2 of relay OS(3), contact 'I and winding of relay SL(3) to battery. Relay SM2) operates in this circuit but the resistance of relay SL(2) is such that relay SL(3) does not operate. When relay SL(2) operates, a circuit is closed from battery through the winding of relay SLI 2), contact I of relay SL(2), to ground. Relay SLI (2) operates and locks over its contact 2, conductor 202 to ground at contact 3 of relay TKS(2). With relay SL|(2) operated, the low resistance right-hand winding of remy sL 2 is connected over contact I of relay SLI (2) to ground at contact I of relay MRL(2).

` The completion of this circuit reduces the resistance in the circuit of relay SL(3) suiliciently to permit that relay to operate. Relay SL(3) locks over its contact 8 to ground at contact 9 of relay OS(3), and at its contact 9 extends the circuit of relay SL(2) through resistance SV(3) to signaling conductor 308 to which the composite signaling circuit 320 has connected ground as above described. Relay SL(2) therefore now releases, completing a circuit from ground, contact 2 of relay SL(2), contact 2 of relay SLI (2) to battery through the winding of relay OP(2).

Relay OP(2) operates and locks disconnecting relay SL(2) from the circuit in which it previously operated. At its contact I, relay OP(2) closes an obvious circuit for operating relay OPI (2).

At its contacts I and 3, relay OPI (2) further opens the circuit of relay SL(2) and at its contacts 2 and 4 extends conductors 200 and 20| over circuits not shown through the winding of relay OF(2), winding of relay TG(2) to battery.

This circuit extends from conductors 200 and 20| by way of the incoming and outgoing trunk circuits to conductor 308 as above traced. The sender, by means of this circuit looks at the trunk and determines the on-hook and off-hook conditions set up by the distant office. Ground on conductor 308 is an on-hook signal, and if present when relay OF(2) and TG(2) are connected to conductor 308, relay OF(2) operates. removal of ground from conductor 308 as above described when the distant sender is ready to receive pulses, releases relay OF(2) When relay OF(2) operates, it operates relay OFI (2) which locks under the control of relay MRL(2)L When relay OF(2) releases it closes a circuit from ground over its contact 2, contact 2 of relay OF|(2), contact 5 of relay OPI(2) to battery through the winding of relay OP2(2). Relay Oli-2 extends conductors 2| 6 and 2|'I to the outpulsing circuit 250, which is controlled by the recapture circuit 259 to send out the digits registered on register 25|. For the further `operation of the sender in connection with a completed call, reference may be made to the McKim- Strickler patent.

If, when the trunk circuit of Fig. 4 attempts to call in a sender, all of the senders are busy, each of the senders 450, 45|, 452, etc., will have released its associated sender idle relays 400, 40|, 402, etc. in the link control circuit 410 and a chain circuit is closed for operating sender group busy relay 41| in the sender link 404. With relay 41| operated, two frequencies from the multifrequency source 43 will be connected to conductors 474 and 415 and in multiple over other contacts of relay 47| to all incoming trunks. A plurality of relays like relay 41| would probably be required to supply the necessary number of contacts. The two frequencies used will represent a code not otherwise used, for example frequencies of 700 cycles and 1700 cycles.

Y When an incoming trunk such as the trunk of Fig. 4 has been seized and is waiting for a sender to be attached, relay LC(4) is operated and relay 00(4) is not operated. At this time conductor 414 is connected over contact 2 of relay 00(4), contact 2 of relay LCM) and condenser R|(4) to conductor 3|0, while conductor 415 is connected over contact of relay CO(4) and contact I of relay LC(4), through condenser TI (4) to `conductor 309.

Thel

In the sender, following the complete registration of the line designation, a start signal made up of 150G-cycle and F700-cycle current is received. The l'lOO-cycle current causes the opera-V tion of relay IA(2) followed by the operation of relay RST(2) in response to the 150G-cycle current, the latter relay locking over its contact 2 to off-normal ground. With relay RST(2) operated and relay OF(2) not yet operated, before the sender at the distant oice has indicated that it is ready to receive pulses, a circuit is closed from ground at contact 2 of relay OF(2), contact l of relay OFI (2), contact l of relay RST(2) to battery through the winding of relay LKA(2) Conductors 30S and 3l!) are connected as previously traced to conductors 209 and Zlil. With relay GP2 (2) not yet operated and relay LKAQ) operated, conductors 299 and 2li) are extended over contacts 2 and i of relay OP2(2) and contacts l and 3 of relay LKAQ) to the multifrequency receiver 25e. This connection may 'occur briefly during a normal call, but in the absence of the all senders busy signal is without effect. When relay OF(2) operates, followed by the operation of relay OFHZ) the circuit of relay LKA(2) is opened and that relay releases, disconnecting conductors 209 and 2li) from the mul-tifrequency receiver 250.

If, during the time that conductors 209 and 2 I El are connected to the multifrequency receiver, the all senders busy signal has been extended thereto as above traced, the HOO-cycle current causes the operation of relay lllA(2) as before. With relay IQA 2 operated the 'ZOO-cycle current causes the grounding of conductor 26E, completing a circuit over contact 2 of relay lA(2) to battery through the reorder relay RORIQ).V Relay RORHZ) operates and locks over its contact 3 to off-normal ground. At its Contact 4, relay RORI(2) opens the circuit of relay MS2(2), which releases, in turn releasing relay MRUZ). Relay RORHZ) at its contact l opens the circuit of slow-to-release relaiT RO(2). When relay ROIZ) releases, it connects ground over its back contact to the winding of relay MS2(2) causing that relay to reoperate. Relay MS2(2) closes the previously traced circuit for operating the marker connector 252 to connect the sender with an idle marker. Relay RORI (2) at its contact 2 connects ground to conductor 25! to tell the marker that a connection is to be set up to a reorder trunk.

The marker, in response to the reorder signal on conductor 261, connects ground to conductor 262, operating relay MT( 2) which opens the connections with the outgoing trunk. The disconnection of ground from conductor 218 permits the trunk link switches 154 and 254 to release and the trunk circuits of Figs. 3 and 4 to restore to normal.

The marker proceeds to set up a connection to a reorder trunk to which a source of reorder signal is connected and the sender completes its functions as for a manual call in the manner described in the McKim-Strickler patent.

What is claimed is:

l. In a telephone system, incoming trunks, switches, outgoing trunks, originating senders, means responsive to a call on one or said incoming trunks to connect one of said originating senders with said one incoming trunk means to register a designation in said originating sender, switch controlling means responsive to said registration to operate said switches to connect said one incoming trunk and said originating sender with one of said outgoing trunks, incoming senders, means responsive to the connection of said one incoming trunk with said one outgoing trunk to connect one of said incoming senders with said one outgoing trunk, means operated when all of said incoming senders are busy to transmit a multirrequency code signal over said one outgoing trunk to said originating sender and means in said originating sender responsive to said signal to cause the transmission of a reorder signal over said one incoming trunk.

2. In a telephone system, incoming trunks, switches, outgoing trunks, originating senders, means responsive to a call on one of said incoming trunks to connect one of said originating senders with said one incoming trunk, means to register a designation in said originating sender, switch controlling means responsive to said registration to operate said switches to connect said one incoming trunk and said originating sender with one of said outgoing trunks, incoming senders, an incoming sender connector, means in said one outgoing trunk operated responsive to the connection of said one incoming trunk with said one outgoing trunk, means under the control of said connection responsive means to oper-y ate said incoming sender connector to connectone of said incoming senders with said one outgoing trunk, an all senders busy relay in said incoming sender connector operated when all of said incoming senders are busy, means under the control of said all senders busy relay to connect a multifrequency code signal to all of said outgoing trunks, means under the control of said connection responsive means to transmit said signal over said one outgoing trunk to said originating sender and means in said originating sender responsive to said signal to cause the transmission of a reorder signal over said one incoming trunk.

3. In a telephone system, incoming trunks, switches, outgoing trunks, originating senders, means responsive to a call on one of said incoming trunks to connect one of said originating senders with said one incoming trunk, a multiirequency code receiving circuit in said originating sender, means under the control of said multifrequency code receiving circuit to register a designation in said originating sender, switch controlling means responsive to said registration to operate said switches to connect said one incoming trunk and said originating sender with one of said outgoing trunks, registration completed indicating means in said originating sender, connection established indicating means in said one outgoing trunk, incoming senders, an incoming sender connector, means under the control of the connection established indicating means of said one outgoing trunk to operate said sender connector to connect an idle one of said incoming senders with said one outgoing trunk, an all senders busy relay in said sender connector, means to operate said all senders busy relay when all oi said incoming senders are busy, means under the control of said all senders busy relay to connect a multifrequency code signal to all of said outgoing trunks, means under the control oi the connection indicating means of said one outgoing trunk to transmit said signal over said one outgoing trunk to said originating sender, means under the control of the registration completed indicating means of said originating sender to extend said signal to said receiving circuit and means under the control of said receiving circuit to cause the transmission of a reorder signal over said one incoming trunk,

4. In a telephone system, incoming trunks, switches, outgoing trunks, originating senders, means responsive to a call on one of said incoming trunks to connect one of said originating senders with said one incoming trunk, a multifrequency code receiving circuit in said originating sender, means under the control of said code receiving circuit to register a designation in said originating sender, switch controlling means responsive to said registration to operate said switches to connect said one incoming trunk and said originating sender with one of said outgoing trunks, registration completed indicating means in said originating sender, connection established indicating means in said one outgoing trunk, incoming senders, an incoming sender connector, means under the control of the connection established indicating means of said one outgoing trunk to operate said sender connector to connect an idle one of said incoming senders with said one outgoing trunk, an all senders busy relay in said sender connector, means to operate said all senders busy relay when all of said incoming senders are busy.

means under the control of said all senders busy relay to connect a multifrequency code signal to all of said outgoing trunks, means under the control of the connection indicating means of said one outgoing trunk to transmit said signal over said one outgoing trunk to said originating sender, means under the control of the registration completed indicating means of said sender to extend said signal to said code receiving circuit, a reorder signal source, a reorder trunk circuit connected With said source, and means under the control of said code receiving circuit to release said one outgoing trunk and to connect said one incoming trunk with said reorder trunk to cause the transmission of a reorder signal over said one incoming trunk.

MARTIN E. MALONEY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,235,803 Carpenter Mar. 18, 1941 2,293,620 Osten-Sacken Aug. 18, 1942 2,385,228 Ostline Sept. 18, 1945 

